Method and apparatus for the production of music



June 30, 1936. B. F. MlEsfiNE R 3 3 METHOD AND APPARATUS FOR THE PRODUCTION OF MUSIC Original Filed Dec. 14, 1932 IIIIIIKL Patented .June 30,

um'rso STATES PATENT OFFICE- mam monmmam'rusmam. PBODUGI'ION OI .HUSIO Benjaminl'. mm, ran-mam County, N. 3., assigns:- to lliessner Inventions,

corporation Incas olNewJersey'.

original application Deoornba- 14, m1 sum No. 1.154. Divided and usanvil 1:. ms, Serial No. 21,200

cation)!!! II-(Jlalma (mu-ml nator substantiallvunobstructed and consequently providing relatively eiiicient radiation of soimd. At the same time. and particularly in instruments of the grand piano type. a large sound radiation takes placefrom the opposite side of the resonator. Inandne'artheplaneoftheresonatora large cancellation oi one radiation by the other occurs at the longer soimd wave lengths, or lower frequencies. This produces'a serious loss oi eflective amplitude at these frequencies in the region wherein the player and still more particularly the listeners are usually located. 1118' various and respectively dissimilar reflections which may occur to these two radiations before their arrival at any particular point undoubtedly mitigate this loss but by no .means eliminate i According to the present invention the' A tion of one side of the resonator-for exam ie,

the bottom sideof a grand piano soundboard or the back side of an upright piano soundboard-Ha absorbed without being permitted to escape tomthe instrument. In effect the radiation efli' en'- cy-i; e., sound energy output with constant vibratory energy input-of that side of the soundboard is rendered substantially zero. In this way the cancellation abovementioned is obviated.

- At the same time the opportunity is aiforded to regulate the volume of sound output by regulation of the eiiiciency of radiation from the other translating the oscillations into sound, thus providing an instrument whereby direct vibrationsound translation (1. e., by the resonator) or'vibration-sound translation through the intermediaryof electric oscillations" are available each in regulable degree. r Ihus it is an object of my invention to provide an instrument with improved low frequency radiation. It is a firmer object to provide means for improving the low frequency radiation of an instrument of the class described.

It is another object to provide an instrument with a resonator, the tion from one side which is absorbed and from the other side of 5 which is controliably rmulated. It is a still further 0311 to provide an instrument with a resouator. with an alternative or auxiliary translat ing system, and with means controlling the rela-- tive sound radiations from said resonator, and' said translating system. Other and allied ob-. jects will more fully appear from thef ollow ing description and the appended claims. A

In such description reference is had to the .acco drawing, of which Figure 1 is-a partial cross-sectional view of a piano embodying my invention, Figure 1 being taken along the line l--i of I'Igure2; and

- I'lgure 2 isapartial planview thereof with the lid removed.

Reference beinghad to Figure 2, there will be seen a grand pianohaving a rim assembly comprising a rim I, a rim cross-member 2-, and a plu- Y rality oi rim-beams I angularly disposed between I cross-member I and rim I. Spaced above the rim-beams I may be provided"a soundboard or resonator ll, reinforced by ribs on the bottom thereof, and maintained in slightly arched form by compression between rim I and cross-member 2.1 Secured to the top of soundboard l I may be the main or treble bridge 5 and the bass bridge t, over which bridges the strings I may be strung to hitch pins I in plate 9. These parts and their disposition may thus be conventional; and theyappear in cross-section in Figure 1, together with the usual hammers I 9 and dampers 20,

which may be actuated by the customary keyoperated action, not shown. In Figure i there will also be seen the conventional lid 31, hinged to the top of rim I by hinges such as 35; and hav- 40 ing front hinged portion 38.

It will be understood that upon excitation of any string or strings I by the associated hammer II, the resulting vibration of the strings will produce a vibration of the bridges and'the soundboard ll. Sound waves are thereupon radiated from both top and bottom of the latter. Customarily the sound waves radiated from the bottom are unobstructed, excepting to a slight degree by virtue of the rim-beams}. According to my invention, however, this bottom radiation is absorbed and thus prevented from emanating into thesurroundingair I The absorption maybeadvantageousiy accomplished by providing a relatively stiff, but preferradiation reduction under the closed lid condiployed under the closed lid conditions as an alternateto the normal radiation, and as an auxilably vibrationally dead, member i I underneath the rim-beams 3 and. extending over the entire area bounded by the rim I, and cross-member 2. The member ll may conveniently be attached to the bottom of the rim-beams. Supported by this member, and preferably filling the space between the rim-beams and at least thinly covering them,

may be provided'acoustically absorptive material,

only avoid contact with the soundboard ID or ribs 4, but is preferably spaced away from the-latter to provide an air chamber. If this be notprovided or be made too small, excessive damping of the vibration of the soundboard may result; and on this account the customary spacing between rim-beams 3 and the soundboard Iii may be, somewhat increased to advantage. It is con-' venient to provide means for retaining the layer IS in its spacing'from the soundboard. Such means may comprise a light copper wire screen 40 stretched between rim l and cross-member 2.

The only effective sound radiation from the soundboard I0 is now from the top-illustrated side. This radiation is customarily under a considerable range of control by the closing and the opening to diiferent degrees of'the lid 31; and when this is closed, by the closing and opening of the usual separately hinged front portion 35 thereof. It is to be noted, however, that the degree of this control is now considerably increased,

since the normally uncontrolled radiation from the bottom-illustrated side is now absorbed.

The degree of radiation reductionwith lid 31 and its'front portion 36 closed may be further increasedby providing a felt or other absorptive seal 42 between lid and rim, and by providing absorptive material vertically disposed between the front edge of the soundboard and the lid, of course with an appropriate gap for the strings. Such absorptive material is shown below the strings as 44, and thereabove as 45. The latter may be secured 'to a flange 46 carried by and at right angles to the hinged front lid portion 36: the material 45 is thus precluded from interfering with the radiation when the front lid portion is opened.

Various refinements carrying still further the tions may comprise the provision of absorptive material on the entire bottom of lid 3l;the provision of such material in back of the fallboard of the instrument above the keys; and the assembly of the ribs 4 and the parts thereby carried to a modified form of plate, which in turn is vibrationally insulated from the rim, as shown in U. S. Patent No. 1,912,293, issued to me May 30, 1933. This last construction has the advantage of reducing vibration of the rim and parts thereto rigidly secured by conduction from the sound- 7 board and plate, which vibration is to some extent radiated as sound by the rim, etc.

A mechanico-electro -acoustic translating system, the sound radiation from which may been;-

iary thereto under open lid conditions, is illus trated Figure 1. A strip 23 is havinga change rapidly because of the high value of the I conductive top edge 24 ingspaced relation to each of the treble strings; and it will be understood that a similar strip may be provided for the bass strings. This strip is the element of the translating system sensitive to the string vibrations and it may-if desiredfbe' rigidly,=mounted; ;I prefer,

however,to mount it to the soundboard 'I ll; having found this mounting especially adapted for the production of good tonal characteristics. The mounting may be accomplished by inverted T- fshaped" pieces 48, the upright of the T being slotted to receive the strippand the horizontal portion of the 'T being fastened to the soundboard.

The slot may be of such a width that it will fricof the latter in the slot toa position generally as close to the strings as possible'without risk of contact therewith under conditions of maximum vibration of the latter, the strip may be glued or otherwise fastened to its supporting pieces.

Thecon'ductive'edge 24.n1 a y be connected to the grid of a thermionic vacuum tube '25, whose cathode may be energized in any well-known manner, whose anode current may be supplied as from a tap 26 on high voltage battery or other source 2 21, and whose grid may be connected through high resistance 29 to a point rendered slightly more negative than the cathode by virtue of anode current .fiow through condensively by-passedresistance 28. In the anode circuitof tube 25 are connected in cascade potentiometer or output control 34, amplifier 30, pedal-operated potentiometer of volume control 3|, further amplifier 32 and loudspeaker or other electro-acoustic translating device 33. It is desirable to provide elec- 3 trostatic shielding 39 around tube 25 and immediately associated apparatus, and to provide a con- It will be appreciated that between each string I and the conductive surface 24 a small electrostatic capacity exists, and that these capacities in parallel with each other form a total capacity between strings and conductive surface. This capacity is charged from battery or source 21 through resistance 29,,and this charge cannot latter resistance. If new any string I be vibrated in a vertical plane, as by striking by its hammer IS, the capacity between'it and the conductive 2 surface 24 will be varied oscillatorlly' in accordance with the frequency and waveform of the degree; and by virtue of the relatively'cohstant 55 I point of the string opposite the conductive sur-* charge in this capacity the voltage across it will 60 likewise vary. 'The oscillatory variations in this voltage will be seen to be applied to the grid of I tube 25; by this tube and succeeding amplifier il they are amplified; they maybe controlled in respect of amplitude and further amplifled if'oli desired by controls II and andby further amplifier 32, respectively; and finally be translated into sound andradiated assuch by loudspeaker 33.

Thus a mechanico-electroacoustic chain of. translation is *providedwhi ch' While I P ve disclosedmy invention V lectively regulating the efliciencyof radiation from the'other side thereof.

2. In the production of music by a piano, the method of sound output control which comprises absorbing the sound radiation from one side of the soundboard of said piano and selectively regulating the efllciency of radiation from the other side of said soundboard. r

3. The combination witha piano including a soundboard and a plurality of tuned strings on one side of and coupled to said soundboard, of

-means for improving low frequency sound propagation from said soundboard in its own plane, comprising means disposed on the opposite side of said soundboard for absorbing the sound radiation from said last mentioned side.

v 4. The combination with a grand piano includ other side of said soundboard, comprising acous- V,

tically absorptive material disposedon said'secand mentioned side of and in spaced relation to said soundboard. A

6. The combination with a piano including'a soundboard and a plurality of rim-beams in r 3 spaced relation thereto, of sound absorptive means. associated with said rim-beams and at least partially interposed between the same and said soundboard.

7. The combination with a piano including a 5 soundboard and a plurality of rim-beams in spaced relation thereto, of sound absorptive material disposed between said rim-beams, and retaining means for said material secured to the side of said rim-beams further removed from said soundboard.

8. The combination with a piano including a soundboard, of means for absorbing the sound radiation from one side of said soundboard, comprising acoustically absorptive material disposed on said side of said soundboard, and acoustically transparent means for retaining said material in spaced relation to said soundboard.

9. The combination with a piano including a soundboard, of means for absorbing the sound radiation from one side of said soundboard-comprising acoustically absorptive material disposed on said side of said soundboard, said material being graded in softness, and the softest material being nearest said soundboard. I

10. The combination with a piano including a soundboard and a plurality of tuned strings on one side of and coupled to said soundboard: of means disposed on one side of said soundboard for absorbing the sound radiation from said side; and an adjustable closure on the other side or said soundboard, whereby the efficiency of radiation from said other side may be regulated.

11. The combination with a grand piano including a plurality of tuned strings and a substantially horizontal soundboard underneath and coupled to said strings, of means disposed under-. neath said soundboard for absorbing the sound radiation from the bottom of said soundboard; and adjustable lid means above said strings, whereby the efliciency of radiation from the top of said soundboard may be regulated.

BENJAMIN F. 

